yeah sure, 1 min length is totally fine. (there are no restrictions for length)
As you can read in the rules embedded objects are allowed
There won't be an extra judging section for Mediatracker due to the simplified system this time, but in theory judges should consider Mediatracker, when giving a mark. The importance of the Mediatracker can vary for each map individually. While on one map a GPS is totally necligible, it may be important on another map.
Music is fine too (no restrictions for that)
The difficulty depends on what the judges rate. If it is super extremely difficult, you should expect a few judges to say that it is too hart. On the other side a super easy track might be too boring for a few judges.